MXPA04007927A

MXPA04007927A - Multiple magnet transducer with differential magnetic strengths.

Info

Publication number: MXPA04007927A
Application number: MXPA04007927A
Authority: MX
Inventors: Xin Hao
Original assignee: Rockwell Scient Licensing Llc
Priority date: 2002-02-19
Filing date: 2003-02-18
Publication date: 2005-05-16
Also published as: KR100671363B1; RU2004127921A; EP1732196A2; RU2294589C2; CA2475481C; US6812598B2; US20030155828A1; JP4315811B2; DE60325708D1; CN1647353A; AU2003216327A1; EP1490954B1; EP1490954A1; CN1647353B; USRE41626E1; WO2003071665A1; JP2005518774A; US6861772B2; ATE420484T1; CA2475481A1

Abstract

A dynamic magnet system, particularly useful for electrical generation, employs multiple magnets (2, 4) in polar opposition to each for individual movement relative to a support structure (6). The magnets (2, 4) have a critical angle of displacement from a horizontal static position of less than 1 degree, with at least some of the magnets (2, 4) having mutually different properties. With different magnetic strengths, a greater movement is produced for both magnets in response to movements of the support structure, for particular ranges of magnetic strength ratios, than would be the case with equal magnets. The magnet movement can be translated into an electrical signal to power an operating system. Ultra low friction ferrofluid bearings can be used to establish static coefficients of friction between the magnets and support structure less than 0.02, enabling useful power generation from only slight movements of the support structure.

Description

DYNAMIC MAGNET SYSTEM DESCRIPTION OF THE INVENTION This invention relates to dynamic magnet systems, and more particularly to multi-magnet systems used to generate electrical energy. Moving a magnet through a conductive coil induces a current flow in the coil. If the magnet moves from one side to the other in a reciprocal movement, the direction of current flow in the coil will be reversed for each successive stroke, providing an AC current. Several electricity generating systems have been described that make use of reciprocal magnetic movement through one or more coils. For example, in various embodiments of Patent No. 5,347,185, one, two or three rare earth magnets are placed to move linearly from one side to the other relative to one or more coils. The magnets can be fixed and the coil can move up and down relative to the magnet, or by wave action, the coil can be fixed and the magnet can move relative to the coil as by pneumatic pressure, or the housing the coil can be agitated and vibrated as if being carried by a jogger, to cause a reciprocating or oscillating movement of a magnet moving inside the coil. In one embodiment, four magnets are provided in successive polar opposition, with the two fixed end magnets and the free half magnets moving from one side to the other along respective portions of a tube. The two middle magnets are separated from each other by the carrier wave for a half coil, the carrier wave being about twice as wide as any of the middle magnets. In Patent No. 5,818,132, one embodiment describes three moving magnets that are suspended within a vertical tube in polar opposition to one another and to end magnets, with a number of separate coils along the outside of the tube. To decrease the friction between the moving magnets and the tube, the tube is oriented vertically and moves up and down to move the magnets relative to the coils, thereby generating currents in the coils. However, the vertical orientation interferes with the movement of the magnets, which have to fight with gravitational forces to be able to move in relation to the tube. The coupling of the movements of the tube in the magnets in this way is reduced. The present invention provides a dynamic multiple magnet system that achieves a greater coupling between a support structure for the magnets and the movement imparted to the magnets themselves. This allows for greater electrical production for the size and weight of a given device, and also allows the magnets to be oriented for movement in a mainly horizontal direction, thus greatly increasing their sensitivity to the applied movement. These improvements are achieved by orienting a plurality of magnets in polar opposition, for the individual movement in relation to a support structure, with at least part of the magnets having mutually different properties. Magnets can have different magnetic resistances, achieved by various means such as providing magnets with different magnetizations or sizes. Magnets of equal size have different degrees of magnetization, magnets of different sizes with equal unit of degrees of magnetization, or mixtures of the two can be used. Surprisingly, the responses of the magnets to an applied movement of their support structure are greater than for two identical magnets that have the average of their sizes and resistances on specific magnetic resistance ratios. The magnets are preferably provided with ultra low friction ferrofluid supports which establish static coefficients of friction between the magnets and the support structure less than 0.02. The ferrofluid preferably has a viscosity of less than 10 centipoise, and in a particular embodiment comprises an oily medium of light mineral mixed with isoparaffinic acid. The provision of ultra low friction supports allows magnets to be arranged in a generally horizontal orientation, in which its sensitivity to the forces applied on the support structure is significantly improved. With this orientation, the magnets show multiple modes of oscillation that effectively couple many different movements of the support structure into useful magnetic motion. With one or more conductive coils placed to have their turns cut off by magnetic fields in motion, an electrical signal can be generated to power numerous types of operating systems. The critical angle of displacement for the magnets from a horizontal static position is preferably less than 1 degree, and may be less than 10 minutes with an appropriate choice of ferrofluid supports. These and other features and advantages of the invention will be apparent to those skilled in the art from the following detailed description, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic diagram illustrating the use of a two-magnet embodiment of the invention to provide power for an operating system; FIGURE 2 is a schematic diagram of an embodiment of two magnets with magnets of equal size that have different magnetization; FIGURE 3 is a schematic diagram of a three magnet mode of the invention; FIGURE 4 is a calculated scheme of the magnetic speed as a function of time for a system of two magnets with equal magnets, and FIGURES 5 and 6 are calculated graphs that refer to the relative energy production relative to the magnetic mass / magnetization differentials for strong and weak end magnet systems, respectively. The present invention provides more effective and flexible electrical power generation than has previously been available in reciprocal or oscillating magnetic systems. The electricity can be generated effectively from several light movements of the magnet support structure outside of a horizontal plane and / or movements in a horizontal plane. For example, a movement of walking, or other normal movements such as turning, softly gliding, arching or even traveling in a vehicle that is subjected to vibration, can easily generate useful amounts of electricity when the support structure for the magnets is maintained in the hand of the user or in the pocket of a shirt, while light movements outside the horizontal due to the action of waves or wind can also be used for electrical generation. The invention employs multiple magnets that move relative to a common support structure. It is not restricted to the three magnets required by the multiple magnet system of Patent No. 5,181,132, but in fact it can employ virtually any number of magnets, including even numbers. The requirement for a vertical orientation by the multiple magnet system of the Patent No. 5,181,132 is also eliminated, allowing a horizontal magnetic movement that is much more sensitive to the movements of the support structure. FIGURE 1 illustrates the use of the invention to provide power for an operating system. In this embodiment, two mobile magnets 2 and 4 move along the axis of a support structure in the form of a non-magnetic tubular box 6. The magnets are in polar opposition to each other, with their opposite ends of similar magnetic polarity. In this way, the magnets repel each other mutually when they come into proximity. And the fixed magnets 8 and 10 are placed at opposite ends of the box in polar opposition to their respective closest mobile magnets 2 and 4. The ends of the mobile and end magnets facing each other are also of similar magnetic polarity so that the adjacent magnets repel each other. The magnet 2 is illustrated as having a unit size, while the magnet 4 is illustrated as comprising two unit sizes. Since it is assumed that all magnetic units in this mode have equal magnetic resistances, the overall magnetic resistance of magnet 4 will be twice that of magnet 2. For light impacts to the case or light movements of the case outside the horizontal, the magnets 2 and 4 will slide along the case 6 if the static coefficients of friction between the magnets and the case are less than about 0.02. Magnetic movement will generally not occur with higher coefficients of friction in response to the relatively light movements of the box, such as those produced by placing the box in a shirt pocket and walking with it. The use of two magnets in polar opposition to each other with ultra low friction supports has been found to greatly increase the response of the magnetic movement to the movements of the box that are not at the natural frequency of the box with a single magnet, and / or are out of phase with the initial magnetic movement. Surprisingly, it has been discovered that, when the two magnets have different magnetic resistances, both magnets have a greater response to the movements of the box than the two equal magnets of the intermediate magnetic resistance. In other words, start with two magnets of equal magnetic resistance, increase the resistance of one and reduce the resistance of the other causing both magnets to oscillate faster in response to the moves of the box for particular margins of resistance relationships. This larger response directly increases the amount of energy that can be generated with the system. To achieve the desired low level of friction, the ferrofluid supports are preferably used as an interconnection between the magnets and the box. Ferrofluids are dispersions of finely divided or magnetizable magnetic particles that generally vary between about 30 and 150 Angstroms in size, and are dispersed in a liquid carrier wave. The magnetic particles are typically coated with surfactants or a dispersing agent. The surfactants ensure a permanent distance between the particles of the magnet to overcome the attractive forces caused by the Van der Waal forces and the magnetic interaction, and also provide a chemical composition on the outer layer of the covered particles which is compatible with the wave liquid carrier and chemicals in the surrounding environ. Ferrites and ferric oxides used as magnetic particles offer a number of physical and chemical properties to ferrofluid, including saturation magnetization, viscosity, magnetic stability and chemical stability. Various types of ferrofluids are provided by the Ferrotec Corporation (USA) of Nashua, New Hampshire. A patent summary related to the preparation of ferrofluids is provided in Patent No. 6,056,889, while the use of ferrofluid supports in a mobile magnet electric generator is discussed in co-pending Patent Application Serial No. 10 / 078,724, entitled "Electric Generator with Ferrofluid Substrates", filed on the same day as the present invention by the applicants and also assigned to Innovative Technology Licensing, LLC, the assignee of the present invention. The contents of this co-pending application are incorporated herein for reference. The characteristics of ferrofluid and magnets are related. If the magnets have a relatively low magnetic field, a relatively high magnetization ferrofluid should be used. The magnetic fields of the magnets will typically vary from approximately 500-4000 Gauss, and the magnetization of the ferrofluid from approximately 50-400 Gauss. The coefficient of friction of the ferrofluid is approximately related to its viscosity (measured in centipoise (cp)), but not directly. For example, a ferrofluid with a viscosity of 300 cp has been found to have a static coefficient of friction of about 0.015, the ferrofluid of EFH1 of Ferrotec Corporation (USA) has a viscosity in the order of 6 cp and a coefficient of friction static ratio of about 0.002, but a water-based ferrofluid with a viscosity of 5 cp has been found to have a static coefficient of friction of about 0.01. The higher coefficient of friction for the viscosity composition of some lower form has been attributed to a surface tension associated with a water-based solvent. A preferred ferrofluid composition for the present invention has a viscosity substantially less than 5 cp, actually less than 2 cp, and achieves an ultra low coefficient of static friction in the range of 0.0008-0.0012. This is sufficiently sensitive for a magnet in a beam to begin to slip when the beam tilts only about 0.7 degrees out of horizontal. These and other suitable ferrofluid compositions are discussed in co-pending Patent Application Serial No. 10/078, 132, entitled "Mechanical Translator with Ultra Low Friction Ferrofluid Substrates", filed the same day as the present invention by the Applicant Jeffrey T. Cheung, and also assigned to Innovative Technology Licensing, LLC, contents of whose applications are incorporated herein for reference. The composition comprises a mixture of a ferrofluid portion of light mineral oil of EFH1 from Ferrotec Corporation (USA) mixed with two to four parts of isoparaffinic acid, stirred for 24 hours. Suitable sources of isoparaffinic acid are Isopar G and Isopar M hydrocarbon fluids from ExxonMobil Chemical Corp. Undiluted EFHl ferrofluid can also be used. The undiluted EFHl composition has a greater weight bearing capacity than the diluted version, but diluting the composition will retain enough weight bearing capacity for most applications. Other ferrofluids with static friction coefficients of up to about 0.02 can also be used, such as type EG 805 of Ferrotec Corporation (USA), a water-based ferrofluid with a static friction coefficient of about 0.01 and a viscosity of about 5 cp, that the energy production that can be achieved with a static friction coefficient of 0.02 is still approximately 75% of what can be achieved with a zero friction system. Currently, the composition of E G805 is considerably more expensive than the composition of EFHl and has a load bearing capacity in a much smaller way. In general, suitable ferrofluids will provide a critical angle of displacement of a horizontal static position of less than 1 degree to initiate magnetic movement, and with the mixture described around the critical angle is less than 10 minutes.

Returning to FIGURE 1, a ferrofluid within the case 6 is naturally attracted to the poles of the magnets 2 and 4 to form beads 12, 14 and 16, 18 around the end poles of the magnets 2 and 4 respectively. This provides an ultra low friction lubricant which allows the magnets to slide freely with respect to the box. The magnets will move in response to a tilt of the box away from the horizontal, a horizontal movement of the box, or more complex compound movements. The kinetic energy of the mobile magnets is converted into potential energy when they reach their magnets | respective ends, and then again in kinetic energy as they are rejected from the extreme magnets. A pair of conductive coils 20 and 22 are wound on respective halves of the case 6. Alternatively, a single coil that covers the entire length of the movement of the magnet within the case may be employed, but, since two magnets will often be moving in opposite directions, opposite currents can be induced in a single coil during these periods which can lower the overall efficiency of the system. The coils 20 and 22 are connected to respective full wave bridge rectifying circuits 24 and 26, the outputs of which charge the batteries 28 and 30, respectively, within a general operating system 32.

The batteries provide power for an operating device 34, such as an ambient sensor, transmitter, headlight or cell phone, which can be operated by mechanical inputs such as a movement of walking, movement of waves or wind. Alternatively, the bridge outputs can be connected directly to the operating device if real-time power is desired. FIGURE 2 illustrates an alternative embodiment of the invention, with only some magnets and their case shown for simplification purposes, without coils or other circuitry. In this embodiment, a pair of magnets 36, 38 are again retained within a non-magnetic box 40 by magnets 42, 44 ends of opposite polarities. In this case, the magnets are of equal size, but the magnet 38 has a higher degree of magnetization and magnetic field resistance, as indicated by the double magnetization arrows, as opposed to a single magnetization arrow for the magnet 36. The operation of this type of arrangement is generally equivalent to that shown in FIGURE 1, which each of the magnetic sections have equal unit field resistances, with one magnet having two sections and the other having one. In both cases, both magnets will move faster in response to the movements of the box, for particular margins of size and strength ratios, than what can be the case with two magnets that have a field strength equal to the strongest magnet of FIGURE 2. FIGURE 3 illustrates an additional embodiment with three magnets 46, 48 and 50 inside the box 52. In this example, the magnets will have different sizes / resistances of magnetic field, with each traveling over ferrofluid srts of ultra low friction. The larger magnet is shown arranged between the other two, but this order can be varied, as well as the relationships between the magnet sizes / field strengths, within the scope of the invention. Two of the magnets can also be made equal, with the third magnet having a different field resistance. The invention can be generalized to any number of different magnets with at least two having different magnetic resistances, although increasing the number of magnets reduces the effective length of the case left for magnetic movement. FIGURE 4 is a calculated scheme that illustrates the multiple modes of vibration that result from a system of several magnets with ultra low friction srts. This scheme was made with the magnets that were ssed to have equal magnetic field resistances, and indicates the speed of one of the magnets as a function of time. The box is supposed to have a length that can result in a natural frequency of 1 Hz for a single magnet system. With two magnets there are multiple oscillation modes that correspond to the different peaks of speed that occur during every second period for each magnet. This makes the system of multiple magnets more sensitive to the movements of the box that do not agree with the natural frequency of the system and / or are out of phase with the initial magnetic movement. The increased response of multiple magnet transducers with ultra low friction supports is discussed in detail in co-pending Patent Application Serial No. 10/077, 945, entitled "Multiple Magnetic Transducer", filed the same day as this invention by current applicants and also assigned to Innovative Technology Licensing, LLC, contents of which application are incorporated herein for reference. Similarly, multiple oscillation modes are produced with multiple magnets of different field strengths which are the subject of the present invention. FIGURES 5 and 6 show the energy productions calculated for two magnet systems, normalized for the production of energy for a single magnet system, as a function of the magnetic mass and the magnetization ratios. FIGURE 5 presents results when strong fixed-end magnets (11,400 Gauss) were assumed, and FIGURE 6 for weak-end magnets (3,800 Gauss). The results obtained by the magnets of the same magnetic material but of different masses were equivalent to the results for magnets of equal mass but different magnetic resistances. The following assumptions were made: - Strongest magnet size: 2.54cm, diameter, 1.27cm long. - Strength of magnet stronger: 11,400 Gauss. - Tube length: 15.24cm. Size of extreme magnet: 0.95cm in diameter, 0.635cm in length. - Acceleration applied to the tube: 1 meter / sec / sec, alternating for 0.5 sec forward and 0.5 sec backwards, during a frequency of 1 Hz (simulating an oscillating arm). - System without friction. The systems of two magnets produced greater energy production than the systems of a single magnet on particular margins of mass or ratio of magnetization with the margin depending on the resistance of the extreme magnet. With the strong end magnets of FIGURE 5, a significantly improved yield was calculated for ratios of about 0.075-0.2, while with the weak end magnets of FIGURE 6 a significantly improved yield was calculated for the ratios of about 0.35-0.6, with a much smaller peak at approximately 0.04. Since the applied acceleration alternated at a frequency close to the resonant frequency of the single-magnet system, even better results could be expected at frequencies more removed from the resonant frequency, or for random inputs. Also, it is important that higher energy outputs are calculated for the system of two magnets with different sizes of magnets or resistors than for a system of two magnets with equal sizes of magnets or resistances (corresponding to a ratio of 1). In the system of FIGURE 5, this occurred during generally the same range of relationships as when compared to a single-magnet system, whereas in FIGURE 6 this occurred over the full range of relationship. The invention has many applications, of which some include providing power for cell phones, emergency transmitters and environmental sensors, and power generation and battery charging systems in general. Although various embodiments of the invention have been shown and described, numerous variations and alternative embodiments will be presented to those skilled in the art. For example, greater numbers of magnets can be used than in the illustrated systems, or different ultra low friction lubricants that the specific compositions mentioned can be used. Also, instead of placing the magnets inside a housing and winding the coils around the outside of the housing, the elements can be reversed with coils inside a housing and a magnet in toroidal form outside. Accordingly, it is intended that the invention be limited only in terms of the appended claims.

Claims

CLAIMS 1. A dynamic magnet system, characterized in that it comprises: a support structure, at least one magnet oriented to move relative to the support structure, and respective supports that establish static coefficients of friction between at least one magnet and the support structure less than 0.02.
2. The dynamic magnet system according to claim 1, characterized in that the supports comprise ferrofluid support.
3. The dynamic magnet system according to claim 2, characterized in that the ferrofluid supports are concentrated at the ends of each magnet.
4. The dynamic magnet system according to claim 1, characterized in that at least one magnet comprises a plurality of magnets oriented in polar opposition.
The dynamic magnet system according to any of claims 1-4, characterized in that it also comprises at least one conductor oriented with respect to the support structure and at least one magnet so that the movement of at least a magnet induces an electrical signal in at least one conductor.
6. The dynamic magnet system according to claim 5, characterized in that it also comprises an operating system energized by the signal.
The dynamic magnet system according to any of claims 1-4, characterized in that it also comprises a pair of end magnets that limit the travel of at least one moving magnet, the end magnets oriented in polar opposition to the respective moving magnet. closest .
8. The dynamic magnet system according to claim 4, characterized in that the magnets have multiple modes of oscillation with respect to the support structure.
9. The dynamic magnet system according to claim 3 or 7, characterized in that the magnets comprise an even number of magnets. The dynamic magnet system according to any of claims 4 or 8, characterized in that at least one of the magnets has mutually different properties.